There are plenty of flies, as well as bees, buzzing the garden flowers these days. Macro close-ups of some of them reveal some interesting features.
Tachinid flies are parasites (coexist inside the host) or parasitoids (use the host’s body for development, ultimately killing it) on a multitude of host species: beetles and beetle larvae, butterfly and moth caterpillars, true bugs, grasshoppers, even other flies.
Specialized ovipositors enable the female to pierce the cuticle of potential hosts to insert her egg; the larva hatches within a few days to immediately begin consuming organs of the host. Some Tachinid fly species lay their eggs on the plants consumed by the host so that eggs are ingested and then hatch in the digestive organs of the host. Sounds gruesome, but these flies are actually good bio-control agents for some insect pest species. In addition, the adults which feed on nectar, are pretty effective pollinators for many plant species.
Both larvae and adult Picture-winged Flies are saprophagic, meaning they feed on dead and rotting plant material, especially bulbs of onions, iris, rotting fruit, etc. In fact, they are most often found near garbage dumps and will lay their eggs right in the rotting vegetation to hatch and complete larval development. The heat of plant decomposition probably helps speed their development along. The first batch of larvae to develop in the spring will complete their pupal development to adulthood and start the life cycle over again. But successive generations of these flies are very photoperiod sensitive, with late summer larvae going into a diapause (like hibernation) for the remainder of the summer and winter, finally completing their pupal development the following spring. Pretty smart for a bug!